Vapor separating pump and impeller



June 2 4, 1947. M. L. EDWARDS I VAPOR SEPARATING'PUMP AND IMPELLER Filed July 1'4, 1945 l Huf: owe-u. "bnvmeos `ugalpumpimpellers Patented June 24, 1941 UNITED' s'rli'rusg *PATENT orale-E 2,422,856 varon. sername ruin' amV nu meu miniem wh. y

' 1 This invention relates to devices for separatlng vapors from liquids, and for free liquid..

Speciilcally, the

liquids. and propel the Dumps so that only pumped.

A feature of separated vapors from the fully liquid material is this invention is the provisionv of screw vanes pump together of! liquid aroundseparate vapor therefrom gally discharge the liquid. o

The pumps of this invention are especially adapted for submersion in ponds of liquid material, and function to pump only fully liquid material from the pond while ilowing vapors in the liquid back to the pond. In pumps of this type, it is highly desirable to effect vapor sepal'tion before the vapors can be trapped in the pump, so that they can be easily released without appreciable power requirements. l

The pumps and impellers of this invention are @Specially adapted for use in aircraft fuel systems wherein volatile liquid fuel, such as gasoline, breaks up and vaporizes in the tanks of the aircraft as ,low pressure high altitude conditions are encountered The invention will hereinafter be specifically described as embodied in a booster pump for an aircraft fuel system, but it should be understood, of course, that the devices of this invention are generally useful for vapor and liquid separating purposes, and for pressuring fully liquid materi i An object of this invention is to provide a pump and motor unit adapted for insertion in a pond of liquid, and having an impeller which simultaneously creates a ilow of material through the pump, a separation of the material into its gaseous and liquid components, and a pressuring of the liquid component into a chamber of the pump.

Another object of this inventio'nis to provide an impeller for a liquid and vapor separating pump which has a ring of centrifugal impeller vanes equipped with generally Z-shaped inner ends to create vapor separating chambers therebetween and to scoop material into these chambers. Y

Anotherobject of this invention is to provide a pump impeller having radially disposed rotating separating chambers, scoops for feeding material into these ,chambers, and propellers for sweeping vapors out of the upper ends of the chambers. y f

A still further object of this invention is to provide a vapor and liquid separating pump impeller which has a central axial ilow passageway therethrough the passageway,

` rounding the screw manson my 14, 194s, sei-nl N. somo-1 Y 11 Claims. (ClvIOL-113) vchambers in a z f through. propellers ior inducing upward ilow l a plurality o! elongated vapor-separating chambers of appreciable'area around the periphery of said passageway and extending up to the propellers, forwardly projecting vanes for slicing material kfrom said passageway into said chambersy ing vanes for centriiugally ilinging out fully liquid material from the chambers.

A speciilc object o! a pump impeller having a hub,- s'crew vanes extending radially irom the huba shroud ring survanes, an outturned ilange on the shroud ring, and a ring of impeller vanes depending from the flange and having offset inner legs extending from the screw vanes and projecting radially and forwardly beyond the inner face of the shroud ring.

A further speciiic object of this invention is to provide a. pump impeller for vapor separating pumps which has enlarged vapor separating equipped with forwardly projecting walls to direct material into the chambers as the impeller is rotated.

A still further object of the invention is to provide a vapor separating pump impeller of increased vapor separating and pumping capacity.

Other and further objects of the invention will be apparent to those skilled Ain the art from `the following detailed description of the annexed sheet of drawings which, by way ofv preferred examples only, illustrate two embodiments of the invention.

On the drawings: Y

Figure 1 is a broken fragmentary vertical crosssectlonal view, with parts in elevation, of a vapor separating pump and motor unit according to this invention mounted in a tank and showing the impeller for the pump in section along the line I--I of Figure 2.

Figure 2 is an enlarged bottom plan view of the pump impeller for the pump shown in Figure 1.

Figure 3 is an enlarged fragmentary horizontal cross-sectional view of a` portion of .the pump impeller taken along the line IIL-III of Figuro 1.

Figure 4 is a view similar to 'Figure 3 illustrating a modified vane arrangement for the pump impeller.

As shown on the drawings: In Figure l, the reference numeral l0 designates generally afuel tank having a bottom wall ilia with a large aperture Illb therethrough.V The tank I0 represents an airplane fuel tank vented to the ambient air.

and centrifugal pumpthis invention is to provide liquid iiow path through the pumpv -arating vanes I3 to the tank. A gasket I5 is interposed between the flange I3a and the bottom wall Illa of the tank to seal the aperture Ilib.

The mounting base I3 is connected through spaced ribs such as I6 with a pump casing I1 defining an annular volute chamber I8 around and in communication with a, central open-ended passageway I9. The volute chamber I8 discharges through a peripheral outlet passageway into an upstandingpassageway 2| defined by a tubular boss member 22 which isintegral with the base I3 in spaced lateral relation from the casing I1. The tubular boss 22 extends beyond the-bottom of the base I3 and receives a conduit fitting 23 in the lower end thereof. A cap 24 closes the top end of the boss, and a single bolt 25 is passed through' the fitting 23` and threaded into the cap 24 to clamp the fitting and cap on the opposite ends of the boss. Gaskets 26 are interposed between the ends of the tubular boss 22 and the cap and conduit fitting.

Liquids from the volute chamber are propelled through the passageway 20 into the passageway 2I and thence through the conduit tting 23 to the fuel line (not shown) of an aircraft fuel system. The fuel line customarily supplies the engine-driven main fuel pump of the system (not shown).

The base I3 has a separate closure plate 21 secured therearound by means of cap screws 28 and maintained in sealed relation with the base by a gasket 29. This closure plate 21 is beneath the outer wall Illa of the tank and provides a sump S for the tank. A drain plug 30 is threaded into the plate 21 ancl can be removed to drain the sump.

A throat ring 3I is secured to the bottom face of the casing I1 by means of cap screws such asl 32. This throat ring -3I defines an inlet I for the pump communicating freely with the sump S. The sump S, in turn, communicate freely with the interior of the tank I0.

The casing I1 has an upstanding leg 33 carrying a base 34 for a motor casing 35. An electric motor in the casing 35 has thel drive shaft 36 thereof extending through thev base 34 and carrying an impeller 31 for the pump. The impeller 31 has a hub 31a fitting over the lower' end of the shaft 36 and held thereon by means of a nut 38. A key 38a fits in complementary slots of the hub 31a and shaft 36 to connect the impeller and shaft for corotation.

A plurality of propellers or screw vanes 31b project radially from the hub 31a and are integral with the hub. Eight vanes are shown, but any number can be used, provided that the same number of centrifugal pumping and vapor separe used as hereinafter described. These vanes 31b are pitched, to induce an upward fiow of material through the passageway I9 of the pump. A shroud ring 31c is secured to the outer peripheries of the vanes 31h. This shroud ring has close-running clearance relationship with the upper end of the passageway I9 and has an outturned flange 31d at thev lower endthereof extending into a peripheral gap 39 connecting the passageway I9 with the volute chamber I8. This ange 31d is preferably mounted so as to have close-running clearance yblade faces 40d beneath relationship with the wall of the vpump casing I1 defining the top end of the gap 39. a

A plurality of vanes 4I) equal in number to the `screw vanes 31h depend from the flange 31d in spaced relation to provide a ring of vanes. The throatring 3| has a bottom flange portion 3Ia receiving the lower ends of the vanes 40 in close-running clearance relation thereabove. The throat ring has a, diverging side Wall 3Ib extending fromI the ange 3Ia to the gap 39. The vanes 40 have outer side edges 49a in close-running clearance relation to the side wall 3Ib of the throat ring, and have narrow upper and.

outer end portions 0b extending into the gap 39.

The inner edges 40e of the vanes 40 converge inwardly from the inner end of the flange 3Ia into the shroud ring 31e and terminate level with the leading lower edges of the screw vanes 31b as best shown in Figure 1.

The vanes 40 provide substantially tangential the shroud ring ange 31d increasing in width along the diverging edges 40a to extended shallow faces 40e lying in the gap 39. These faces 40d and 40e provide fiingers for centrifugal discharge of liquid from the portion I9a of the passage I 9 surrounded by the vanes.

The inner portions of the vanes 40a, as best shown in Figures 2 and 3, are offset at 0f to extend substantially radially toward the passage I9a. wardly projecting inner legs or ends 40g. The forwardly projecting legs 40g cooperate with the radially extending portion 40j to provide, between the inner ends of the vanes, vapor separating chambers C having enlarged areas. Since the inner edges 40e of the vanes converge to lie radially inward of the shroud ring 31e at their upper ends and terminate at the lower edges of the screw vanes in the gaps between the screw vanes, the tops of these chambers are extended to the screw vanes and are uncovered at their inner ends. The 'extension of the individual chambers into the shroud ring and up to the propeller or screwvanes 31h insures rotational movement of material treated in the chambers up to the point of discharge of the material out of the pump thereby eliminating any dead pockets between the chambers and discharge point.

The .contour of the radial portions 0f and forwardly projecting leg portions 40g in the embodiment shown in Figures 1 to 3 is such as to provide scoop-like leading faces 40h in angular relation to the faces 40d of the vanes. .The legs 40g have a positive rake or pitch such that inner edges 40e are sharp and are the innermost portions of the vanes. Theseinner edges llic should all be equidistant from the axis of rotation o1 the.

impeller.

In operation of the pump, liquid, such as gasoline from the tank I0, is strained through a screen 4I surrounding the pump casing to ll the sump S and the entire passageway I9 of the I These radial portion* 401 have for-v seminato-Y endstoformlocalisedeireulatingpoolsinthe separating C the scoop-like innerendsofthevan Thesecirmrlatingpools or'eddy currents of liquid and viper are held closely adjacent the inner ends of the vanes and extend at their inner ends up to the screw vanes 31h. These screw vanes create an upward axial flow'of material through the passageway Iland sweep the' vapor-ladenliquid in the circulating pools upwardly and out of the open tops ofthe pool chambers.' The heavier fully liquid material' is centrifugally discharged through the channels between the vane faces e into the volute chamber Il.

A decided advantage in altitude performance of the pumps was obtained by extending the legs Ila vto meet the propeller blades lfb. and overhang the gaps between the blades 11b as shown with the number of propeller blades and the number of vanes ll being equal- This 'extension of the legs up to the propellers .forces rotation of fuel up to the' point of discharge back to the fuel tank and allows gas and vapors upward under influence of gravity from the centrifugal pumping chambers into the propeller chamber. Thus as failure occurs in a pump, the vspaces scribed vby ythe revolving vanes becomes filled with gas bubbles which form. gas-filled pockets or cavities acting as a'restriction to flow of liquid.v Any separation the pumping vanesfrom spaces scribed by the propeller vanes will leave a zone between the two spaces which can become gas bound to impede dow to the propellers and cause early pump failure. The forced rotation of fuel between the pumping valles and the propeller vanes eliminates gas binding in the zone between the pumping varies and propellers and actually merges the gas separating chambers toprovide extended chambers C.

As shown by thearrows inFigure 3, liquid in the peripheral portion of the passage Hals sliced od or scooped up by the forwardly legs 40g of the vanes. The lighter bubble-laden liquid is directed by the radial portions l0! of the varies to form an eddy current in the relatively large chamber C between a pair of vanes `while the heavy fully liquid material is thrown outwardly by centrifugal force through a restricted throat T between the vanes. Since the inner end of the chamber C is uncovered, the vaporrich liquid is discharged out of the pump as explained above. The tangential portions 40d of the vanes 40 act as tangential ingersto throw the heavier fully liquid material through the restricted throat T between the varies. The centrifugal discharging force of the vanes will, of coursekpump liquid into the volute chamber, but before this liquid is pumped, it-must pass from a relatively largelow velocity separating chamber C through the restricted high velocity throat T. The vane design is such that the lighter vaporladen liquid and the bubbles of gas and vapor are caused to form an eddy current or recirculating pool within the centrifuge chamber The inner ends of the vanes keep the bubbles in this chamber until they are discharged upward through rotating channels and, at the'same time, the forwardly projecting ends of the scoop-like portions of the vanes continue to slice liquid from the periphery of the passage portion isa into the separating 'chambers to increase the pumping capacity of the pump and to prevent the pump from becoming gas-bound in the separating chambers. These scoop-like inner ends of the of spaces scribed by projecting 31h 0f the impellel vanes feed the separating n pump!!! channels between the vanes but, at the. same time, hold the bubbles in the separating chambers imtil they are swept out of the :piper ends of the chambers by the screw vanes In themodiflcation shown in Figure 4, the impeller Il' having the same screw vanes, d ring and shroud ring nauseas the impeller l1 is equipped with modified vanes 4I depending from the shroud ring flange "d, These modified venes have edges as the vanes ll and have the same deep inner vane portions and shallow outer vane portions arthe vanes 4I. However, the inner ends of the vanes have thickened .radially inwardly extending portions lla with cut-out leadingfaces 'IIb forming pockets discharging closer to the to flow freely inner end of the preceding vane than the scooplike Vfaces ofthe vanes Il. Thus, as shown in Figure 4, the radial vane portions 42a have forwardly projecting faces llc-terminating in a reentrant pocket 2b with the end of-this pocket facing the preceding vane close to the inner end of the vane. A vapor-separating chamber C' is thus formed very close to the inner ends of the vanes and is only slightly covered by the shroud v ring flange 31d. The recirculating po'ol or eddy through the pump so .trifugally discharge current of vapor-laden fuel is thus kept closer to the inner ends of the varies. The heavier liquid discharged from the pocket 2b is directed against the tangential face of the preceding vane and must pass through the restricted high velocity throat T before it can enter the volute chamber.

From the above descriptions it should be understood that this invention provides a vapor and liquid separating pump wherein an axial flow of -liquid is induced through the pump, and wherein a centrifugal pumping of fully liquid material free from gas and vapors is obtained. The pumps'of this invention have impellers so constructed and ar'ra'nged as to create recirc'ulatingv pools or eddy pump and to prevent vapors and gases from being centrifugally discharged. The vanes of these impellers sliceoff or scoop up material around the periphery of a pond in the pump to release vapors and gases from the the gases and vapors in the path of axial flow that they will be swept out of the pump. At the same time the vanes centhe fully liquid material under pressure. yThe scooping up or slicingoif of material from the pond prevents the pump from becoming gas-bound and at the same time increases the pumping capacity of thev pump. Pumps equipped with the impellers of this invention have more than twice the pumping capacity of pumps equipped with standard centrifugal impellers.

It will, of course. be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, notthe pur- .pose to limit the patent granted hereon otherchambers and the the same tapered' inner and outercurrents of liquid andK vapors to release vapor-rich material out of the material and t0 hold a plurality of elongated relatively large separatl ing chambers, and forwardly extending legs on said end portions arranged to scoop material in the passageway into said separating chambers.

2. A pump comprising a casing having an openended passage therethrough with a communicating pump chamber therearound, an impeller in said passage having spaced propellers for inducing axial flow through the passage, said impeller having a ring of vapor separating and pumping.

vanes thereon surrounding a central inlet passageway in said open ended passage and providing channels therebetweendischarging into the pumping chamber, said vanes having relatively deep inner end portions and relatively shallow outer end portions, and substantially Z-shaped leading ends on said inner end portions of the vanes projecting into said passageway and deilning therebetween separating chambers of relatively large area communicating with said channels through restricted throats, said Z-shaped inner ends having legs projecting forwardly to slice off material in said passageway, said legs extending up to the propellers and overhanging the spaces between the propellers, and said Z- shapedinner ends having front faces for directing the sliced off material to create eddy currents in said separating chambers communicating freely with said propellers.

3. A pump impeller comprising a hub, 'spaced propellers extending radially from said hub, a shroud ring surrounding said propellers, an outturned flange on said shroud ring, and a plurality of vanes depending from said flange in spaced relation around the flange, said depending vanes having offset inner ends with forwardly projecting legs extending into the shroud ring up to the propellers.

4. A pump impeller comprising circumferentially spaced pumping vanes having open inner ends defining a ring, said vanes extending outward from the ring to define pumping channels therebetween arranged to receive fluids from the space inside of the ring, the inner ends of said vanes extending radially inward and forwardly to provide scoop-like faces extending into the space inside of the ring for defining therebetween relatively large vapor separating chambers.

5. A pump impeller comprising an open ended cylindrical member having an outturned flange at one end thereof, pumping vanes depending from said flange beyond said member, said vanes having inner edges extending inwardly beyond the inner end of the flange and providing scooplike leading faces disposedl outwardly from the axis of the impeller, a hub for said impeller, and

' screw vanes connecting the cylindrical member .and hub arranged to induce axial ilow of material to sweep bubbles of gas and vapor from the chambers between the scoop-like faces of the vanes.

6. A pump impeller comprising a ring of circumferentially spaced centrifugal pumping vanes, each of said vanes having arradially inwardly extending inner end portion and a forwardly projecting end on said inner end portion, and said vanes being so4 constructed and arranged to denne therebetween relatively large 8 vapor separating chambers for low velocity recirculation of material together with relatively small pumping channels for high velocity discharge of vmateriaLsaid channels communicating with said chambers through restricted throats. 1

7. A pump impeller comprising a ring of circumferentially spaced centrifugal pumping vanes having radially inwardly `extending thickened portions, the forward faces of said thickened portions having reentrant recesses providing localized scoop-like chambers arranged for eddy current circulation of material sliced off from the space Within said ring.

8. A pump impeller comprising a plurality of circumferentially spaced propeller vanes, a ring of centrifugal pumping vanes spaced from the propeller vanes. said pumping vanes being equal in number to the propeller vanes, and forwardly4 andinwardly projecting legs on the in'ner ends of the pumping vanes extending to the propeller 'vanes for defining rotating vapor-separating chambers between the the propeller vanes.

9. A pump impeller comprising a hub, a relatively large Anumber of circumferentially spaced propeller vanes extending radiallyfrom said hub, a shroud ring surrounding said propeller 'vanes and joined thereto, circumferentially spaced centrifugal pumping vanes depending from said shroud ring, said pumping vanes being equal in number to said propeller vanes, and each pumppumplng vanes joined with ing vane having a radially offset inwardly ex-y tending portion with a forwardly projecting leg extending into the shroud ring to terminate level with the lower leading edge of a propeller vane andl overhanging the gap between said propeller vane and the next adjacent propeller vane.

10. A pump impeller comprising an annular member supporting a plurality of circumferentially spaced centrifugal pumping vanestherearound, the inner ends of said vanes defining an axial flow passage and the outer ends definingv centrifugal pumping channels therebetween, said inner vane ends having portions projecting radially inwardly and forwardly to an increasing degree along said passage in the direction of iiuid flow, thereby defining vapor separating chambers between said inner vane ends.

11. A pump impeller comprising an annular member supporting a 'plurality of circumferentially spaced centrifugal-pumping vanes therearound, the inner ends of said vanes defining an axial flow passagel and the outer ends defining centrifugal pumping channels therebetween, said inner vane ends having portions projecting radially inwardly and forwardly to define vapor -separating chambers between said inner vane ends, and propeller means immediately adjacent one end face of said inner vane ends for producing axial flow of vapor-rich fluid from said chambers.

MILES LOWELL EDWARDS.

REFERENCES CITED UNITED STATES PATENTS Number 1 -Name Date 2,242,714 Willson May 20, 1941 

